The proposed study will examine the social communication and neuroanatomical correlates of autistic disorder (i.e., qualitative impairment in social interaction, qualitative impairment in communication. restricted repetitive stereotyped patterns of behavior. interests. and activities) in a cohort of surgically treated children with infantile spasms. We will also examine the degree of tuberous sclerosis (TSC)-like changes and cortical dysplasias in the resected brain tissue of these children. and determine its correlation with the diagnosis of autism. Specific Aims 1. We will examine the hypothesis that surgically treated children with infantile spasms who meet criteria for autistic disorder have specific social communication deficits (i.e., underutilization of joint attention and social interaction, impaired distribution of positive affect during nonverbal communication) at the 2 year follow-up after surgery compared to those who do not meet criteria for autistic disorder. 2. We will examine the hypothesis that the resected hemisphere of the surgically treated infantile spasms patients who meet criteria for autistic disorder has more severe cortical dysplasia with TSC-like lesions than the patients who do not meet criteria for autistic disorder. 3. We will test the hypothesis that, compared to the children who do not meet criteria for autistic disorder, the nonresected hemisphere of the children who meet criteria for autistic disorder will have: a) presurgical FDG hypometabolism of the temporal, parietal, and/or frontal lobes b) postsurgical MRI evidence for increased volume of the nonresected hemisphere and reduced area of cerebellar lobules VI and VII. 4. We will examine hypotheses that an intact remaining hemisphere can support social communication by determining if the postoperative change in specific social communication behaviors are associated with presurgical FDG metabolic patterns.